I. Field of the Invention
A rotatory abdominal crunch machine relates to a machine that assists the user in swinging his or her body to strengthen the muscles, particularly to a machine that assists the user in swinging his or her waist in circular motion so as to achieve powerful and tight abdominal muscles.
II. Description of the Prior Art
Each of the abdominal workout equipment in the market has its own motion design that assists the user in strengthening the muscles of different parts. The swing machine of the prior art mainly uses a rotating disc to assist the user's workout for strengthening the muscles. With reference to FIG. 1, which is a three-dimensional explored diagram showing a swing machine of the prior art, the swing machine 10 comprises a support rack 101, a seat rack 102, a rotating disc 104, and a seat 105. The support rack 101 is used to support the seat rack 102. The rotating disc 104, which is fitted on the seat rack 102, comprises a surface disc 1042, a base disc 1042 and a rolling element 1043, which is embedded in said base disc 1042. Surface disc 1041 of the rotating disc 104 is fitted beneath a seat 105. An anti-slip belt 1031, which girds said surface disc 1041, holds a pound-force adjuster 1032 on one of its ends. The rolling element 1042 embedded in the rotating disc 104 allows said rotating disc 104 to rotate. The user sits on seat 105 fitted on the rotating disc 104 and swings his or her waist so as to strengthen the abdominal muscles. However, the swing machine of the prior art not really offers circular motion that allows the user to completely exercise the abdominal muscles.